Prolonged immobility can also increase the risk of deep vein thrombosis, particularly during long journeys or when additional risk factors are present.
To reduce the effects of inactivity:
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Stand up and move around regularly when it is safe to do so.
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Flex and extend your ankles while sitting.
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Take short walking breaks during long periods at a desk.
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During travel, move your legs frequently and walk when practical.
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Avoid remaining in a cramped position for extended periods.
If you are at increased risk of blood clots because of previous thrombosis, recent surgery, cancer, pregnancy, or another medical condition, ask a healthcare professional whether additional preventive measures are appropriate during long journeys.
Do not assume that swelling after travel is simply the result of sitting. Sudden one-sided swelling, calf pain, or warmth requires urgent assessment.
13. Heart Failure: When Fluid Builds Up in the Body
One of the more important causes of persistent swelling in both legs is heart failure.
Heart failure does not mean that the heart has stopped working. It means that the heart cannot pump blood or fill with blood adequately enough to meet the body's needs without increased pressure.
When pressure builds up in the circulation, fluid may move into surrounding tissues. In some people, this produces swelling in the feet, ankles, and lower legs. Fluid may also accumulate in the abdomen or lungs.
Other symptoms can include:
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Shortness of breath during activity.
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Difficulty breathing when lying flat.
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Waking during the night feeling breathless.
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Unusual fatigue or reduced exercise tolerance.
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A rapid increase in body weight over a short period because of fluid retention.
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Abdominal fullness or swelling.
Not everyone experiences all these symptoms. Some people develop swelling gradually, while others notice a sudden worsening.
Heart failure can have many causes, including coronary artery disease, previous heart attacks, long-standing high blood pressure, certain heart muscle diseases, and valve disorders.
Diagnosis usually involves a medical history, physical examination, blood tests, and other investigations. Depending on the situation, clinicians may order an electrocardiogram, chest imaging, or an echocardiogram to assess heart structure and function.
Treatment depends on the underlying cause and may include medications, dietary adjustments, monitoring of fluid status, and management of related conditions.
If you develop severe shortness of breath, chest pain, fainting, confusion, or blue or gray discoloration of the lips, seek emergency medical care.
New leg swelling combined with worsening breathlessness also warrants urgent medical assessment.
14. Kidney Disease and Fluid Retention
The kidneys help maintain the body's balance of water, sodium, potassium, and other substances. They also remove waste products from the blood.
When kidney function declines, the body may retain more salt and water than it needs. This can contribute to swelling in the feet, ankles, legs, hands, or around the eyes.
Certain kidney conditions also cause the body to lose excessive amounts of protein through the urine. When blood protein levels become low, fluid may move more readily from blood vessels into surrounding tissues.
Possible accompanying symptoms include:
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Puffy eyelids, especially in the morning.
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Changes in how often you urinate.
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Foamy urine that may indicate excess protein.
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Fatigue or reduced appetite.
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Nausea.
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High blood pressure.
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Swelling in other parts of the body.
However, early kidney disease may cause few noticeable symptoms. Some people have no obvious swelling at all.
A healthcare professional may evaluate kidney function using blood tests, urine tests, blood pressure measurements, and other investigations when necessary.
People with kidney disease should be particularly cautious about trying to treat swelling themselves. Drinking excessive amounts of water, taking diuretics without supervision, or making extreme changes to salt intake can be harmful in certain circumstances.
The appropriate fluid and sodium recommendations depend on kidney function, the cause of swelling, medications, and other health conditions.
If you have known kidney disease and notice new or worsening edema, contact your healthcare team for advice.
15. Liver Disease Can Also Cause Swollen Legs
The liver produces albumin, a protein that helps keep fluid within blood vessels. It also plays a central role in metabolism, digestion, and the processing of many substances.
Advanced liver disease can affect albumin production and increase pressure in the blood vessels that carry blood through the liver. These changes can contribute to fluid accumulation in the legs and abdomen.
Abdominal fluid buildup is called ascites.
Depending on the underlying condition, other signs may include:
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Increasing abdominal size.
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Yellowing of the skin or eyes.
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Easy bruising.
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Reduced appetite.
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Unexplained fatigue.
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Itching.
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Changes in mental alertness in advanced disease.
These symptoms are not specific to liver disease, and some people with liver problems have few early warning signs.
Possible causes of chronic liver disease include certain viral infections, long-term harmful alcohol use, metabolic dysfunction-associated steatotic liver disease, and autoimmune or inherited conditions.
Evaluation may include blood tests, imaging, and other investigations selected according to the suspected cause.
People with liver disease should not assume that swollen legs can be managed simply by drinking less water or taking over-the-counter products. Fluid management may require careful medical supervision.
16. Deep Vein Thrombosis: A Blood Clot That Must Not Be Missed
Deep vein thrombosis, or DVT, occurs when a blood clot forms in a deep vein, usually in the leg.
The clot may obstruct blood flow, causing fluid to accumulate in the affected limb. DVT may produce swelling, pain, tenderness, warmth, or changes in skin color.
One leg may become noticeably larger than the other, although symptoms vary. Some people have very few obvious symptoms.
Risk factors include:
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Recent major surgery or hospitalization.
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Prolonged immobility.
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Previous DVT or pulmonary embolism.
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Certain cancers and cancer treatments.
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Pregnancy and the period after childbirth.
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Estrogen-containing medications.
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Some inherited clotting disorders.
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Other conditions that increase the risk of thrombosis.
A DVT is dangerous because part of the clot can break off and travel to the lungs, causing a pulmonary embolism.
Warning signs of pulmonary embolism include sudden shortness of breath, chest pain that may worsen with breathing, coughing up blood, a rapid heartbeat, or fainting.
If you have sudden swelling in one leg, especially with pain, warmth, or redness, seek urgent medical assessment. If you also develop breathing difficulty, chest pain, coughing up blood, or fainting, call your local emergency service immediately.